Spring unit for stripper devices



Dec. 25, 1951 H. .J. ALDRICH SPRING UNIT FOR STRIPPER DEVICES Filed Oct. 14. 1947 INVENTOR HARRY J. ALDRICH ATTORNEYS Patented Dec. 25, 1951 SPRING UNIT FOR STRIPPER DEVICES Harry J. Aldrich, Lansing, Mich., assignor to Motor Wheel Corporation, Lansing, Mich., a corporation of Michigan Application October 14, 1947, Serial No. 779,829

4 Claims. (01. 164-410) 1 i This invention relates to a spring unit and more particularly to a stripper spring unit which is particularly useful in presses, such as stamping, punching and shearing presses, for stripping the by telescoping cups 4 and sufficiently sothat the open end l2 of cup 4 can be die formed to form a circumferential shoulder l3 which cooperates with circumferential flange l4 on cup 5 to work from the tools or dies. 5 hold cups 4 and 5 in telescoping relation and It is old in the art to use spring stripping units permanently connected. Cap screw 9 is fitted with punch and shearing presses either alone for loosely in the aperture 10 and can be operated by directly stripping the work from the dies or in means of a hexagonal shaft or Allen screw wrench conjunction with a stripper plate which is actuinserted through opening [5 in the bottom of ated by these spring stripping units. The spring cup 5 and threaded opening [6 in part I and enstripping units of the prior art have had certain gaging the socket IT in the head of cap screw 9. defects, to wit; the spring ofeach unit is exposed In Fig. 1 I have shown a die assembly for so that the spring upon breaking or failing will punching holes in a sheet metal part Hi. The die fly out of the punching press constituting a hazassembly comprises a plate l9 which is attached ard for the punch press operator; the unit has to to the punch press head (not shown) and moves be turned or screwed into the die and this makes upwardly and downwardly, stationary plate the unit difficult to assemblefor disassemble from which supports the die 2|, punch 22 which is the die; also severe strain is set up between the mounted on plate I!) by tool holder 23, stripper parts of the unit when screwed inplace by means plate 24 and locating stud 25 which positions part of a wrench. i I8 in correct position preparatory to the punch- It is an object of this invention to produce a ing operation. spring unit which overcomes the objections or Stripper plate 24 is mounted upon plate is by disadvantages of the spring units of the prior art, a plurality of stripper spring units generally deswhich is of simple structure, strong, easily as- 25 ignated 26 (only one of which is shown). Each sembled and disassembled from the die, and which unit 26 is secured in a recess 2'! in plate: I!) by inlends itself readily to lubrication. .serting an Allen wrench through openings i5 and A further advantage of my spring unit is that IS and into socket ll of cap screw 9 which is the spring element of the unit can be much screwed into threaded opening 28 in plate [9. stronger than the springs of the prior art thereby Stripper plate 24 is secured to stripper spring unit reduc the n mber of spring units required i 26 by means of an Allen head can screw 29 which any structure in contrast with the number of is passed through an opening 30 in plate 24 and Prior t Spring ts ed 0 t S S r screwed into threaded opening H5 in bushing I. ture. It will thus be seen that each spring unit 26 is My invention also contemplates a spring unit easily assembled to. and disass mbled from, plate wherein the spring is enclosed within a housing I9 and stripper plate 24 without placing any so that upon failure of the spring it cannot fly out of place.

In the drawings:

Fig. 1 is a vertical section through a die assembly for punching holes in a sheet metal part strain upon the telescop ng housing 4, 5 and spring element 5. The spring element is enclosed within the tele copic housing where it can be effectively lubricated inasmuch as the telescoping cups 4 and 5 form an excellent grease retaining showing my spring units supporting the stripper structure. With my spring unit if the spring plate, should fail. the unit does not fall apart but re- Flg. '2 is a longitudinal section through my tains its unit structure and no parts of my spring spring unit, unit can get into the die structure where they Fig. 3 is a section along the line 3-3 of Fig. 2.

My spring unit consists of five members-cup 4. cup 5 mounted in telescopic relation with respect to cup 4, spring 6, internally threaded bushing 1 welded or otherwise secured to the bottom 8 of cup 5 and cap screw 9.

The ;unit is assembled by first placing capscrew 9 through aperture ill in the bottom ll of cup 4, placing the spring 6 in cup 4 and placing cup 5 over the end of spring 6 which projects from cup 4, and then compressing spring 6 and therewould cause damage. Further, if the spring fails, it is enclosed with n the telescopic housing and cannot fly out, thus making it much safer for the press operator.

The load capacity of my spring unit is dependent upon thespring which is used. Various load capacities can be obtained by using different springs, all other parts being unchanged. In the unit illustrated in the draw ings, spring 6 is preloaded to approximately 150 pounds and requires about 350 pounds pressure to compress the unit one-quarter of an inch. This has been found to be good practice for the majority of die constructions upon which this unit is used.

In Fig. 1 the die assembly is shown closed so that the pressure upon stripper plate 24 has compressed or collapsed the spring unit 26 a small distance, say, about one-quarter of an inch. As the die assembly opens, spring pressure in the spring units 26 forces stripper plate 24 against part l8 and strips this part from punch 22 to which it has a tendency to stick.

I claim:

1. A spring unit comprising a pair of telescoping cup members, a coil compression spring mounted within said cups with its ends resting upon the bottom walls of said cups, opposed :holes in the bottom walls of said cups axially aligned with each other and with the coil spring, the inner cup having a circumferential outwardly projecting flange 1311 0111151 the of its sidewall sand the outer cup having an inwardly projectingiflangearound the trim "oiitssidewal-l interengag-ing beneath :th-efiange on the rather cup member, the -distance between "the bottom ivalls of said cups .when their respective fianges are in abuttingirelationrbeing'less Qthan thesaxial length of said spring whereby .the spring ..-is preloaded and an internally threaded bushingfixed within and to the bottom Wall of tone cup with a threaded pening aligned -.with '.the opening ,in the bottomwall o'fthe said cup,,andla cap screw loosely positionedlin the .opening in theio'ther of said cups and with/its head within said other cup and aligned withsaid openings in 'saidione :cupiand'bushing whereby said cap screw can be turned by passing an instrument through. the iopeningsin the'said one cup and said'hushing.

'2.I"In combinationwitha die and stripper plate for aisheet metalipress, a's'tripper spring unit for yiel'dablymounting the stripper plate on the die comprising a pair of telescoped cup membersya "preloaded coil spring housed ,within said :cups with "the'ends of said'springcontacting the bottom walls of said cups, axiallyaligne'd opposed "openings in the bottom ,walls or said cups :and V "positioned substantially along the longitudinal axis of said coil spring, a screw passing loosely through one of said openings for threaded engagement with one of said press members, the said screw having its head within one of said cups and being adapted for turning by passing an instrument through the opposed opening in the other cup and securing means mounted in the other opening for securing'the unitt'o the other plate.

of said press members, and means integral with said cups for retaining the cupsrin telescoped :relation with the coil spring preloaded and for supporting the stripper plate when the press is "open.

3. The :combination asset forth in claim 2 wherein the said-:means comprises an outward- "lyturnedifiange upon the rim of the inner telescoping cup and an inwardly turned flange on the rim or the outer telescoping cup which overlies thfeaforementioned flange to retain the cups in telescoped relation whereby when the press iswopen, the cups carry thelloadofrsaid stripper 4. Elie combination as .set forth ,in claim .3 wherein the telescoping cups are metal stampings, and an internally threaded bushing -fixed to the inside face .of thebottom wall :of the lone vfile of :this patent:

i UNITED swarms :PA'mN'rs Number Name Date T960395 .Pofihla e't 311...- June 1 7,, 1910 1,137,,145 Krarup ,l -i .l Apr. 27,, 1915 2324,65? Wales July 20, ,1943 2,334,138 7 Wales Nov. .9, Q1943 FOREIGN PATENTS Number Country Date 156,863 7 '(Frreat Britain Jan.2Q,QI921 223,062 'GreaitBlitain Oct. 16,1924 

